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G R Johnson

Publications and source records attributed to G R Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1998

A study of the dimensions and taper angles of the medullary canals of the proximal and middle phalanges.

The morphology and dimensions of the medullary canals of the proximal and middle phalanges have been studied with particular interest shown to the angle of taper of these canals. Measurements of 50 cadaveric fingers were taken from computer aided tomographic images using AutoCAD software. Tangents were fitted to the inner cortices in two orthogonal planes and the angles between them were measured. The angles of canal taper in the proximal phalanx were remarkably similar for each digit. This was also true for the middle phalanx of the index, middle and ring fingers but the taper of the middle phalanx of the little finger was found to be different.

Aged↗
PubMed1997

Amphiregulin antisense oligonucleotide inhibits the growth of T3M4 human pancreatic cancer cells and sensitizes the cells to EGF receptor-targeted therapy.

Human pancreatic cancers overexpress the epidermal growth factor (EGF) receptor (EGFR) and all 5 ligands that bind to this receptor, including amphiregulin. It is not known, however, whether amphiregulin contributes in an autocrine manner to enhance pancreatic cancer cell growth. Therefore, we used an amphiregulin antisense oligonucleotide (AR-AS) to suppress amphiregulin expression in T3M4 human pancreatic cancer cells. These cells express high levels of EGFR and amphiregulin. AR-AS abolished amphiregulin immunoreactivity in T3M4 cells, decreased amphiregulin release into the medium and inhibited cell growth in a dose-dependent manner. Exogenous amphiregulin reversed AR-AS-mediated growth inhibition. A random oligonucleotide (AR-R) did not alter either cell growth or cellular amphiregulin immunoreactivity. AR-AS also increased cellular EGFR protein levels and enhanced the growth-inhibitory actions of TP40, a chimeric protein consisting of transforming growth factor-alpha coupled to Pseudomonas exotoxin that internalizes into cells via EGFR. These findings indicate that there is an important EGFR/ amphiregulin autocrine loop in T3M4 cells and raise the possibility that modalities aimed at abrogating amphiregulin action may prove useful in pancreatic cancer, especially when used in conjunction with EGFR-targeted therapy.

Amino Acid Sequence↗
PubMed1997

Prevalence and associations of abdominal aortic aneurysm detected through screening. Aneurysm Detection and Management (ADAM) Veterans Affairs Cooperative Study Group.

BACKGROUND: Independent risk factors for abdominal aortic aneurysm (AAA) have not been clearly defined in multivariable analyses of large patient populations. OBJECTIVE: To identify factors that are independently associated with AAA and to determine the prevalence of previously unrecognized AAA in defined demographic and risk groups. DESIGN: Cross-sectional screening study. SETTING: 15 Department of Veterans Affairs medical centers. PARTICIPANTS: 73451 veterans who were 50 to 79 years of age and had no history of AAA. MEASUREMENTS: The results of ultrasonographic screening for AAA and a prescreening questionnaire were analyzed using multiple logistic regression. RESULTS: An AAA of 4.0 cm or larger was detected in 1031 participants (1.4%). Smoking was the risk factor most strongly associated with AAA; the odds ratio (OR) for AAAs of 4.0 cm or larger compared with normal aortas (infrarenal aortic diameter < 3.0 cm) was 5.57 (95% CI, 4.24 to 7.31). The association between smoking and AAA increased significantly with the number of years of smoking and decreased significantly with the number of years after quitting smoking. The excess prevalence associated with smoking accounted for 78% of all AAAs that were 4.0 cm or larger in the study sample. Female sex (OR, 0.22 [CI, 0.07 to 0.68]), black race (OR, 0.49 [CI, 0.35 to 0.69]), and presence of diabetes (OR, 0.54 [CI, 0.44 to 0.65]) were negatively associated with AAA. A family history of AAA was positively associated with AAA (OR, 1.95 [CI, 1.56 to 2.43]) but was reported by only 5.1% of participants. Other independently associated factors included age, height, coronary artery disease, any atherosclerosis, high cholesterol levels, and hypertension. CONCLUSIONS: Abdominal aortic aneurysm is associated with multiple factors. Smoking was the risk factor most strongly associated with AAA and may be responsible for most clinically important cases of previously undiagnosed AAA.

Aged↗
PubMed1997

Cytokine receptor expression on hematopoietic stem and progenitor cells.

Hematopoietic stem and progenitor cell populations were obtained by fluorescence activated cell sorting of murine bone marrow (BM) cells into Rhodamine-123io lineage-Ly6A/ E+ c-kit+ (primitive stem cells highly enriched for long-term BM repopulating activity), Rhodamine-123med/hl lineage- Ly6A/E+ c-kit+ (mature stem cells highly enriched for shortterm BM repopulating activity and day 13 spleen colony-forming activity) and lineage- Ly6A/E- c-kit+ (enriched for in vitro colony forming cells) populations. Neither stem cell population responds to single cytokines in vitro and each requires the synergistic action of two or more cytokines for proliferation, whereas the progenitor cell population proliferates in response to single cytokines. Since each of these cell populations was sorted as c-kit+, they express receptors for stem cell factor. Cell populations were also analyzed by autoradiography for their ability to specifically bind iodinated cytokines and this revealed that both stem cell populations expressed receptors for interleukin-1 alpha (IL-1 alpha), IL-3, IL-6, and granulocyte colony-stimulating factor (G-CSF), but lacked receptors for macrophage colony-stimulating factor (M-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), and leukemia inhibitory factor (LIF). Cells within the progenitor cell population specifically bound IL-3, GM-CSF, G-CSF, IL-6, and IL-1 alpha, whereas no receptors were detected for M-CSF and LIF. Within each cell population examined, heterogeneity was observed in the percentage of cells labeled and the number of receptors per cell. These results suggest that stem cell populations can be further subdivided according to their cytokine receptor profile and it will be of interest to determine if such subpopulations have distinctive functional properties.

Animals↗
PubMed1997

Expression of epidermal growth factor-related proteins in the aged adult mouse mammary gland and their relationship to tumorigenesis.

Mammary glands from female BALB/c mice of different ages and parity were screened for production of three epidermal growth factor (EGF) related transforming growth factors and their corresponding mRNAs. Glands were obtained from 2-26-month-old nulliparous, 4-26-month-old parous, and 2-8-month-old midpregnant mice. Reverse-transcribed polymerase chain reaction (RT-PCR) was used to screen for mRNA from the transforming growth factor alpha (TGF alpha), cripto-1 (CR-1), and amphiregulin (AR) genes in extracts of whole mammary glands. TGF alpha, CR-1, and AR transcripts were detected in all of the mammary glands assayed. In situ hybridization was then used to localize these mRNAs among various cell types in sections of glands. TGF alpha mRNA levels were low in the mammary epithelium from young nulliparous mice, high in the stroma of midpregnant mammary glands, and highest in luminal epithelium of the aged glands. AR mRNA levels were high and remained unchanged in all developmental stages. CR-1 mRNA level increased with age and was detected primarily in epithelium, with some scattered expression in adjacent stroma. Finally, TGF alpha, CR-1, and AR proteins were immunolocalized in histological sections of mammary glands from the various developmental stages. TGF alpha was detected sporadically in midpregnant mice, with more conspicuous reactivity seen in 18-26-month-old mice (38% of mice). CR-1 immunoreactivity was detected in 100% of the 18-26-month-old glands but not in any other age groups. Strong AR immunoreactivity was observed in in all glands, including 100% of the 18-26-month-old glands. Staining for all three of these growth factors was observed primarily in the epithelium, with some reactivity detected in the periductal fibroblasts. No significant difference was discerned between glands from nulliparous and parous animals. We also found intense CR-1 and AR mRNA expression and strong immunoreactivity in seven different carcinogen-induced and eight spontaneous mammary tumors. Our results demonstrate that these growth factors accumulate in significant amounts in the old gland of both nulliparous and parous mice. The observations suggest that these growth factors are positioned to contribute to abnormal development in the older mammary gland, predisposing them to tumorigenesis.

Aging↗
PubMed1997

Evidence that initiated keratinocytes clonally expand into multiple existing hair follicles during papilloma histogenesis in SENCAR mouse skin.

We have previously shown that the precursors of cutaneous papillomas in SENCAR mice initiated with 7,12-dimethylbenz[a]anthracene and promoted with 12-O-tetradecanoylphorbol-13-acetate are focal hyperplastic lesions that we refer to as squamous cell hyperplastic foci (SCHF). Ha-ras gene codon 61 mutations were frequently found in SCHF, providing evidence that these lesions represent clones of initiated cells. We report here the pathogenesis of multiple hair follicle involvement in more advanced SCHF and describe the role of the hair follicle in papilloma histogenesis. Detailed histological evaluation of 83 SCHF and 25 early papillomas revealed a morphological continuum from the least developed SCHF, involving only one hair follicle, to advanced SCHF and early papillomas, which involved more than 10 hair follicles. These results provide evidence of the recruitment of additional hair follicles as SCHF progress. In advanced SCHF and early papillomas the bulk of the epithelial component in all cases consisted of several markedly hyperplastic adjacent hair follicles, whereas the involved interfollicular epidermis (IFE) was generally less hyperplastic. All of the hair follicles involved in SCHF appeared to have been preexisting, based on their pattern of spacing, that they were consistently normal appearing below the level of the sebaceous glands, and that they were in the same phase of the hair cycle as surrounding, uninvolved hair follicles. Also, no evidence of follicular neogenesis was observed in serially sectioned SCHF, and coalescence of smaller lesions was rare. To investigate whether the involvement of multiple hair follicles in SCHF was due to expansion of initiated cells into existing hair follicles or, possibly, to a paracrine mechanism, we analyzed different levels of three serially sectioned SCHF and one early papilloma for Ha-ras mutations. These analyses revealed cells with Ha-ras gene codon 61 mutations at multiple levels that involved different hair follicles. Overall, our results provide evidence that as initiated cells clonally expand, they spread across the IFE and populate the upper permanent portions of existing hair follicles. The abnormal proliferation of the infundibula of the hair follicles involved in SCHF appears to give rise to most of the epithelial component of papillomas.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

A case report: immune responses and clinical course of the first human use of granulocyte/macrophage-colony-stimulating-factor-transduced autologous melanoma cells for immunotherapy.

The first use of granulocyte/macrophage-colony-stimulating-factor-transduced, lethally irradiated, autologous melanoma cells as a therapeutic vaccine in a patient, with rapidly progressive, widely disseminated malignant melanoma resulted in the generation of a novel antitumour immune response associated with partial, albeit temporary, clinical benefit. An initially negative reaction to non-transduced, autologous melanoma cells was converted to a delayed-type hypersensitivity (DTH) reaction of increasing magnitude following successive vaccinations. While intradermal vaccine sites showed prominent dendritic cell accrual, DTH sites revealed a striking influx of eosinophils in addition to activated/memory T lymphocytes and macrophages, recalling the histology of challenge tumour cell rejection in immune mice. Cytotoxic T lymphocytes (CTL) reactive with autologous melanoma cells were detectable at high frequency after vaccination, not only in limiting-dilution analysis, but also in bulk culture without added cytokines. Clonal analysis of CTL showed a conversion from a purely CD8+ response to a high proportion of CD4+ clones following vaccination. A prominent acute-phase response manifested by a five- to tenfold increase in C-reactive protein was observed, as was a systemic eosinophila. Vaccination resulted in the regression of axillary lymphatic metastases, stabilisation of pulmonary metastases, and a dramatic, reversible increase in cerebral oedema associated with multiple central nervous system metastases: however, lesions in the adrenal glands, pancreas and spleen proved refractory. The antitumour effects and immune response were not detectable 2 months following the last vaccination. Irradiation of the extensive cerebral metastases resulted in rapid deterioration and death of the patient.

Autopsy↗
PubMed1997

Relationship of age, gender, race, and body size to infrarenal aortic diameter. The Aneurysm Detection and Management (ADAM) Veterans Affairs Cooperative Study Investigators.

PURPOSE: To assess the effects of age, gender, race, and body size on infrarenal aortic diameter (IAD) and to determine expected values for IAD on the basis of these factors. METHODS: Veterans aged 50 to 79 years at 15 Department of Veterans Affairs medical centers were invited to undergo ultrasound measurement of IAD and complete a pre-screening questionnaire. We report here on 69,905 subjects who had no previous history of abdominal aortic aneurysm (AAA) and no ultrasound evidence of AAA (defined as IAD > or = 3.0 cm). RESULTS: Although age, gender, black race, height, weight, body mass index, and body surface area were associated with IAD by multivariate linear regression (all p < 0.001), the effects were small. Female sex was associated with a 0.14 cm reduction in IAD and black race with a 0.01 cm increase in IAD. A 0.1 cm change in IAD was associated with large changes in the independent variables: 29 years in age, 19 cm or 40 cm in height, 35 kg in weight, 11 kg/m2 in body mass index, and 0.35 m2 in body surface area. Nearly all height-weight groups were within 0.1 cm of the gender means, and the unadjusted gender means differed by only 0.23 cm. The variation among medical centers had more influence on IAD than did the combination of age, gender, race, and body size. CONCLUSIONS: Age, gender, race, and body size have statistically significant but small effects on IAD. Use of these parameters to define AAA may not offer sufficient advantage over simpler definitions (such as an IAD > or = 3.0 cm) to be warranted.

Aged↗
PubMed1997

Drugs in salmonid aquaculture--a review.

In contrast to mammalian therapeutics, the use of pharmaceutical substances is rather limited in fish. It is basically restricted to anaesthetic agents and anti-infective agents for parasitic and microbial diseases. Anaesthetic agents are used primarily in fish farm and laboratory settings to provide analgesia and immobilization of fish for minor procedures. The anti-infective agents are used for controlling diseases and the choice of drug depends on efficacy, ease of application, human safety, target animal safety including stress to the fish, environmental impact, regulatory approval, costs, and implications for marketing the fish. In this article, the major drugs used in salmonids in North America and Europe will be reviewed and some insight into future directions for drug development and use for the salmonid industry will be introduced. The mechanisms of action, pharmacokinetics, side effects, and uses of the drugs are emphasized.

Anesthetics↗
PubMed1997

Multiple pathways for toluene degradation in Burkholderia sp. strain JS150.

Burkholderia (Pseudomonas) sp. strain JS150 uses multiple pathways for the metabolism of catechols that result from degradation of aromatic compounds. This suggests that the strain also uses multiple upstream pathways for the initial hydroxylation of aromatic substrates. Two distinct DNA fragments that allowed Pseudomonas aeruginosa PAO1c to grow with benzene as a sole carbon source were cloned from strain JS150. One of the recombinant plasmids containing the initial steps for the degradative pathway contained a 14-kb DNA insert and was designated pRO2016. We have previously shown that the DNA insert originated from a plasmid carried by strain JS150 and contained genes encoding a multicomponent toluene-2-monooxygenase (tbmABCDEF) as well as the cognate regulatory protein (tbmR) that controls expression of the 2-monooxygenase (G. R. Johnson and R. H. Olsen, Appl. Environ. Microbiol. 61:3336-3346, 1995). Subsequently, we have identified an additional region on this DNA fragment that encodes toluene-4-monooxygenase activity. The toluene-4-monooxygenase activity was also regulated by the tbmR gene product. A second DNA fragment that allowed P. aeruginosa to grow with benzene was obtained as a 20-kb insert on a recombinant plasmid designated pRO2015. The DNA insert contained genes encoding toluene-4-monooxygenase activity but no toluene-2-monooxygenase activity. The pRO2015 insert originated from the chromosome of strain JS150, unlike the region cloned in pRO2016. Southern blots and restriction map comparisons showed that the genes for the individual 4-monooxygenases were distinct from one another. Thus, strain JS150 has been shown to have at least three toluene/benzene monooxygenases to initiate toluene metabolism in addition to the toluene dioxygenase reported previously by others.

Biodegradation, Environmental↗
PubMed1997

Cross-regulation of toluene monooxygenases by the transcriptional activators TbmR and TbuT.

The toluene-3-monooxygenase from Burkholderia pickettii PKO1 and the toluene/benzene-2-monooxygenase from Burkholderia (Pseudomonas) sp. strain JS150 are distinct enzymes which differ not only in catalytic specificity and substrate range but also in the arrangement and sequence of the genes within the operons that encode the enzymes, tbuA1UBVA2C and tbmABCDEF, respectively. In the present study, we examined the transcriptional activation of the PtbuA1 and PtbmA promoters by their cognate regulators, TbuT and TbmR. TbmR and TbuT each exhibited activation of both PtbmA and PtbuA1, with toluene, benzene, and chlorobenzene serving as strong effectors. These results strongly suggest that TbmR is an NtrC-like regulator which is functionally homologous to TbuT, and they provide evidence for the evolutionary "recruitment" of the same or a similar type of regulator for both monooxygenase pathways.

Base Sequence↗
PubMed1997

Computer simulation of the dynamics of a human arm and orthosis linkage mechanism.

This paper describes the use of computer modelling and simulation during the design and development of a motorized upper limb orthotic system to be used to aid the dysfunctional human arm. The orthosis consisted of a three-degree-of-freedom shoulder module and a lower arm module providing movements at the elbow and wrist. Simulation software has been used to model the mechanism created by the connection of the orthosis and the arm. With this model it has been possible to analyse the kinematics and kinetics of both the arm and orthosis during a variety of dynamic loading conditions. In particular, the power requirements of the orthotic joints during the execution of specific tasks have been determined and these data have been used to specify the motors of a working prototype. The effect of misalignment between real and orthotic shoulder joints has also been investigated and a potentially hazardous situation has been highlighted prior to testing of the prototype by a volunteer in the laboratory.

Arm↗
PubMed1996

Epidermal growth factor induces coupling of protein-tyrosine phosphatase 1D to GRB2 via the COOH-terminal SH3 domain of GRB2.

The Src homology 2 (SH2) and SH3 domain-containing adaptor protein GRB2 and the SH2 domain-containing protein-tyrosine phosphatase 1D (PTP1D, also called SHPTP2, PTP2C, SHPTP3, Syp, or SHP-2) function as positive mediators of growth factor-induced mitogenesis. Epidermal growth factor (EGF) is a potent mitogen for MCF-10A human mammary epithelial cells and EGF receptor-expressing mouse NR6 fibroblasts. Western blot analysis of anti-PTP1D immune complexes derived from EGF-treated cells demonstrated a ligand-dependent coupling between the phosphatase and GRB2 in vivo. Probing of lysates from these cells with glutathione S-transferase (GST) fusion proteins corresponding to the individual domains of GRB2 revealed that this interaction was mediated exclusively by the COOH-terminal SH3 domain of GRB2. Importantly, a GST fusion protein containing the PTP1D SH2 domains was not capable of generating the EGF-induced linkage to GRB2. Additional experiments indicated that neither the binding of the nucleotide exchange factor Sos to GRB2 nor tyrosine phosphorylation of PTP1D was required for EGF-stimulated coupling of PTP1D to GRB2. This is the first demonstration of a growth factor- or cytokine-induced coupling of a protein through an SH3 domain and suggests that GRB2 functions to target PTP1D, in addition to Sos, to the plasma membrane in response to EGF.

Adaptor Proteins, Signal Transducing↗
PubMed1996

COOH-terminal extended recombinant amphiregulin with bioactivity comparable with naturally derived growth factor.

The mature secreted form of the epidermal growth factor (EGF) receptor ligand amphiregulin (AR) is reported to be an 84-amino acid residue polypeptide, which is generated by proteolytic processing of a 252-amino acid precursor. This form of recombinant AR (rAR84) and two forms with COOH-terminal extensions corresponding to sequences from the AR precursor (rAR87 and rAR92) were expressed at high levels in Escherichia coli, oxidized to the correct disulfide arrangement, and purified to homogeneity. rAR84 competed poorly for binding of radiolabeled EGF to the EGF receptor and had little ability to stimulate growth of Balb/c/3T3 cells. In striking contrast, rAR87 and rAR92 possessed 42- and 20-fold greater receptor binding activity and 55- and 14-fold greater bioactivity, respectively. Furthermore, addition of the COOH-terminal four amino acids from transforming growth factor alpha to the COOH terminus of rAR84 improved the activity of rAR84 by 100- and 1000-fold, respectively, in these assays. rAR87 was found to have approximately 32% of the specific activity of natural AR from MCF-7 cells when compared in two different bioassays. These findings strongly suggest that the 84-amino acid sequence is not the correct structure of the naturally occurring secreted form of AR and that natural AR contains additional amino acid residues at the COOH-terminal end.

3T3 Cells↗
PubMed1996

STAT activation by epidermal growth factor (EGF) and amphiregulin. Requirement for the EGF receptor kinase but not for tyrosine phosphorylation sites or JAK1.

The epidermal growth factor (EGF) receptor activates several signaling cascades in response to the ligands EGF and amphiregulin (AR). One of these signaling events involves the tyrosine phosphorylation of STATs (signal transducers and activators of transcription), a process believed to require the activation of a tyrosine kinase of the JAK family. In this report we demonstrate that EGF- and AR-induced STAT activation requires the intrinsic kinase activity of the receptor but not the presence of Jak1. We show that both wild type (WT) and truncated EGF receptors lacking all autophosphorylation sites activate STAT 1, 3, and 5 in response to either EGF or AR. Furthermore, relative to cells expressing WT receptor, ligand-induced tyrosine phosphorylation of the STATs was enhanced in cells expressing only the truncated receptor. These results provide the first evidence that (i) EGF receptor-mediated STAT activation occurs in a Jak1-independent manner, (ii) the intrinsic tyrosine kinase activity of the receptor is essential for STAT activation, and (iii) tyrosine phosphorylation sites within the EGF receptor are not required for STAT activation.

Amphiregulin↗
PubMed1996

Characterization of a novel amphiregulin-related molecule in 12-O-tetradecanoylphorbol-13-acetate-treated breast cancer cells.

Amphiregulin (AR) can be induced at the mRNA level by 17-beta-estradiol (E2) or the phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). This study compares the effects of TPA and E2 on the regulation of processing of AR isoforms and on subcellular localization in human MCF-7 breast cancer cells. AR was localized in the nucleus of MCF-7 cells after E2 treatment, whereas it was predominantly secreted after TPA treatment. AR isoforms of 28, 18, and 10 kDa and an additional species of approximately 55-60 kDa were detected in the cellular conditioned media after TPA stimulation. Expression of this unusual AR isoform was inhibited by protein kinase C (PKC) inhibitors such as bryostatin or H-7. The biochemical properties of this isoform are consistent with it being an N-linked glycosylated form of the AR precursor that contains unprocessed mannose residues. The size of this large isoform is reduced to approximately 40 kDa after treating the TPA-induced MCF-7 cells with tunicamycin or treating the conditioned media of such cells with N-glycosidase F or with endoglycosidase H. Moreover, this isoform is able to blind several lectins with specificity for mannose residues. The 55-60 kDa glycosylated AR isoform, like lower Mr AR isoforms, is able to bind to heparin and to stimulate the growth of MCF-10A cells by interacting with the EGF receptor. These data suggest that TPA activation of PKC may be involved in post-translational modifications of AR, such as glycosylation, and in alteration of its subcellular routing to predominantly a secretory pathway.

Amphiregulin↗
PubMed1996

Modelling the muscles of the scapula morphometric and coordinate data and functional implications.

Modelling of the shoulder mechanism is dependent upon reliable data on the morphometry and points of attachment of the relevant muscles. In this paper, the authors present coordinate data which have been derived from the radiography of dissected cadavers. All of the coordinates have been normalised with respect to reference dimensions of the relevant segments (humerus, scapula, clavicle and trunk). Similarly the measurements of physiological cross-section area (PCSA) have been normalised with respect to that of deltoid. The measurements of PCSA have been shown to agree largely with the work of Veeger et al. [J. Biomechanics 24, 615-629 (1991)] and Karlsson and Peterson [J. Biomechanics 25, 189-199 (1992)]. While the majority of the descriptions of morphometry concur with accepted texts there are some notable disagreements, particularly concerning trapezius.

Anatomy, Cross-Sectional↗